On Friday 8 March there is free admission to many of Rome's municipal museums, on the occasion of International Women's Day.
The two non-participating museums are the Planetarium, where the ordinary entry fee applies; and the Capitoline Museums, where a reduced fee will apply along with the usual ticket price for the exhibition "Tiffany and Gallè" at Palazzo Caffarelli.
For full details, in English as well as other languages, see the city museums' website.